Red Flag Warning 19, NWS Denver/Boulder, CO

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1146 AM MDT Wed Mar 11 2026

.KEY MESSAGES...

- Prolonged period of widespread critical fire weather conditions
  is expected Thursday through Saturday as successive downslope
  wind events impact the Front Range.

- Mountain snow expected to develop late Saturday following a cold
  front, with precipitation potential and cooler temperatures
  extending into the lower elevations through Sunday.

&&

.DISCUSSION /Through Tuesday/...
Issued at 1155 PM MDT Tue Mar 10 2026

Current trends necessitated some changes to our short-term forecast
grids for this overnight period, with low and mid-level moisture
spilling over the Continental Divide and into the urban corridor and
plains in the wake of the frontal passage. Snow showers have become
more expansive with gradual moistening of near-surface conditions,
so have introduced higher PoPs and lowered snow levels to account
for the potential for a few areas of light snow accumulations up to
1", mainly on colder surfaces. In the mountains, 2-5" can be
expected through the next few hours, with locally slick conditions
and travel impacts for the passes. Shower activity should subside by
around 3AM Wednesday.

Expect cooler highs Wednesday in the wake of the front, mostly in
the low to mid 50's for the plains. Clear skies will prevail and the
jet will remain fairly close just to our north, and with quite
efficient mixing, breezy conditions will continue in the high
country and also portions of our northeast plains, with near-
critical fire weather conditions in place.

Healthy amplification of the surface low on Thursday across the
northern CONUS will support rapid strengthening of east-west
pressure gradients, set to peak Thursday afternoon when cross-
barrier flow up to 65 kts is indicated. Cross-sections suggest
mountain wave development beginning near daybreak, with the axis of
strongest winds centered over our foothills above 7,500 ft, where
the probability of gusts exceeding 80-90 mph is high (75%). There's
some disagreement with regard to inversion placement and duration
however, and wind directions become suboptimal (i.e. more
northwesterly) above ~600mb for downwind amplification, which
notably limits confidence in such strong gusts materializing for
adjacent lower elevations. Most of the higher resolution models
still maintain the core of these winds in the foothills, but we've
seen guidance change quickly in the past within the 12-24 hours
preceding the onset of wind events, so will opt to maintain our
current High Wind Watch for areas along/west of I-25 with this
potential in mind. As is typical, the Highway 93 corridor would be
the most susceptible to incursions of very strong gusts, if that
occurs. In any case, most of the urban corridor and plains will be
exposed to fingers of at least moderately strong winds (gusts 35-50
mph) through the day, which will drive critical fire weather
conditions given renewed low humidity.

Pressure gradients relax Friday, but we'll remain under a warm and
dry subsident flow regime, with healthy flow aloft persisting. As
such, critical fire weather conditions will continue despite some
moderation in the peak strength of the winds.

Our next wind event arrives Saturday as a developing shortwave over
the northern plains nudges the jet stream southward over Colorado.
Downslope winds will strengthen through the day, and mountain wave
potential does exist for the afternoon hours. Critical fire weather
conditions may be more expansive Saturday for the lower elevations
and into portions of the foothills, and we'll be plenty dry and
warm. However, the strongest winds for many areas, including our
plains, may actually hold off until Thursday evening into early
Sunday and be primarily Bora-driven as a robust cold front descends
into the area. This system will begin to increase snowfall chances
in our high country by Saturday evening and, if moisture can
survive, potentially bring some light snow to our lower elevations
as well overnight and into Sunday (~60% chance). Depending on how
much moisture we can hold on to under the northwest flow aloft,
mountain snow could linger into Monday. Temperatures will cool down
considerably for Sunday, but a warming trend will return quickly for
Monday with rapid warming anticipated through next week.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1146 AM MDT Wed Mar 11 2026

VFR to prevail through tonight and Thursday. Winds will continue
to follow an anticyclonic pattern through 00Z Thursday with NE to
E winds at DEN, E to SE winds at APA, and SE winds at BJC. The
winds slowly turn E to SE at DEN, likely ending up southeast
around 00Z. Southerly winds then prevail overnight at the Denver
airports.

For Thursday, channels of gusty west winds are expected to develop
late morning and early afternoon (16-19Z). The threat for gusty
winds (35 knot gusts) will be mainly after 18Z at DEN, but a slight
chance (20-30%) the gustier winds arrive earlier. Along the edges of
the wind channels, rotors/eddies are expected to form, so winds may
end up variable at times if one of these rotors/eddies moves over.

&&

.FIRE WEATHER...
Issued at 1155 PM MDT Tue Mar 10 2026

Wednesday will bring warmer and drier conditions with humidity
lowering to near or slightly below 15% across the plains. There's
potential for efficient mixing to lead to a window or breezier
northwest winds gusting 25-35 mph for the northeast plains this
afternoon, though some weakening is likely as the afternoon
progresses. Patchy critical conditions are thus possible for parts
of our plains today, but confidence in their spatial extent or
duration is not high enough for any headlines.

On Thursday, a strong mountain wave will develop and produce
westerly wind gusts in excess of 80 mph across much of the
foothills, with potential for localized gusts of 60-80 mph for
immediately adjacent lower elevations, where humidity will fall to
near 15%. Critical fire weather conditions will extend into the
plains with gusts above 35-45 mph expected. Overnight recoveries
will be poor along the base of the foothills Thursday night.

Critical conditions will continue Friday, with some moderation in
peak winds, but still retaining some gusts above 30-45 mph for
parts of the plains, urban corridor and lower foothills where
humidity will again be low.

Another wind event is anticipated Saturday with potential for
stronger gusts and mountain wave development, before a potent
front brings a surge of strong winds late in the day. Dry daytime
conditions will be in place leading to widespread critical fire
weather.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from late tonight through late Thursday night
for COZ033>036.

High Wind Watch from Thursday morning through late Thursday
night for COZ038-039-042.

Fire Weather Watch from Thursday morning through late Thursday
night for COZ238-239.

Fire Weather Watch from Thursday morning through Thursday
evening for COZ240-242>245-248>251.

&&

DISCUSSION...BRQ
AVIATION...12
FIRE WEATHER...BRQ

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
458 AM MDT Wed Mar 11 2026

COZ030>051-121100-
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Grand and Summit Counties Below 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Central and Southeast Park County-
Larimer County Below 6000 Feet/Northwest Weld County-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
Northeast Weld County-Central and South Weld County-Morgan County-
Central and East Adams and Arapahoe Counties-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County-
Southeast Elbert County Below 6000 Feet/South Lincoln County-
Logan County-Washington County-Sedgwick County-Phillips County-
458 AM MDT Wed Mar 11 2026

...HIGH WIND WATCH FOR THE FRONT RANGE MOUNTAINS, FOOTHILLS, AND
NEARBY ADJACENT PLAINS WEST OF I-25 AND NEAR THE WYOMING BORDER
STARTING LATE TONIGHT AND THURSDAY, LASTING THROUGH THURSDAY
NIGHT...
...FIRE WEATHER WATCH FOR THE NORTHEAST PLAINS AND I-25
URBAN CORRIDOR STARTING THURSDAY...

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

Today will feature gusty winds to around 35 mph and elevated fire
weather conditons over the northeast plains.

Winds will start to increase over the higher Front Range Mountains
and Foothills late tonight, and strengthen into Thursday morning.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

A prolonged period of significant fire weather conditions is
shaping up for Thursday through Saturday as winds strengthen and
humidities drop. Thursday will feature a potential of high winds
with gusts greater than 60-70 mph near the base of the foothills
and along Wyoming border, and up to 80-90 mph in some of the
foothills and mountains of western Boulder and Larimer Counties.

Friday will likely see critical fire weather conditions again, but
a slight reprieve in the magnitude of winds. Another round of
widespread critical fire weather conditions will be likely again
on Saturday as winds strengthen again in an unseasonably warm and
dry airmass.

A cold front will bring a chance of snow by Saturday night and
Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.